WASHINGTON (CN) – Triggering a collective of citizen sleuths known as Cooperites to circle the wagons, a team of private investigators says their code-breaker has definitively identified the man who hijacked a commercial plane in 1971 and parachuted off with a $200,00 ransom, never to be seen again.

“Our criminal investigation is finished,” said Thomas Colbert, a journalist and film producer who assembled the 40-member team. “We have the man, we know who he is.”

Gathered on Feb. 1 outside of FBI headquarters in Washington, the team said their decryption of several letters sent to newspapers in the days following the skyjacking confirm what they have believed for several years: that D.B. Cooper is Robert W. Rackstraw Sr., a Vietnam war veteran and former U.S. Army paratrooper now living near San Diego.

Rackstraw’s name actually came up in the Cooper investigation in the 1970s, and the connection was spurred on in part by his oblique reply to a NBC News reporter’s on-camera query. “I’m afraid of heights,” the former paratrooper replied with a smile. “Could have been. Could have been. I can’t commit myself on something like that.”

Colbert included the clip in a 2016 History Channel documentary of his earlier findings, but the Washington Post quoted D.B. Cooper authority Geoffrey Gray that year as saying Rackstraw was never a serious suspect.

Military ID photo of Robert Rackstraw from 1970. (National Archives and Records Administration)

Rackstraw has often denied that he is D.B. Cooper, but after Colbert’s Feb. 1 announcement he questioned why he should have to.

“There’s no denial whatsoever, my dear,” the 74-year-old Rackstraw said in a phone interview.

Of Colbert’s investigative team, he added: “Have them sign under the penalty of perjury that everything they stated was true.”

The FBI, which closed its investigation in 2016, has not announced plans to reopen the still-unsolved case.

CRACKING THE CODE

A 1971 artist’s sketch provided by the FBI of the skyjacker known as “Dan Cooper,” or “D.B. Cooper.”

Though the name D.B. Cooper has taken on folk-hero status, it stems from a misidentification by the Associated Press in its initial reporting of the Nov. 24, 1971, hijacking of Northwest Orient Flight 305.

The Boeing 727 was taking off from Portland, Oregon, when a passenger who used the alias Dan Cooper passed a note to a flight attendant that demanded parachutes and $200,000, saying he had a bomb.

When the aircraft landed as scheduled in Seattle, Cooper traded the passengers for the ransom, then directed the pilots to fly to Mexico.

The plane was flying at Cooper’s requested 10,000 feet when he opened its rear staircase and parachuted out somewhere over the Pacific Northwest with the cash.

In the days following the hijacking, as the the largest manhunt in U.S. history turned up few leads, several newspapers received four mysterious letters. Only one was handwritten, but all are signed by D.B. Cooper.

Rick Sherwood, a code-breaker on Colbert’s team, said the first letter, sent on Nov. 27, 1971, contains a hidden message taunting the FBI.

On his website, cold-case investigator Thomas Colbert includes this composite image to demonstrate handwriting parallels between D.B. Cooper and the sender of several taunting letters to newspapers in the days after the 1971 hijacking.

Composed of cutout words and letters, the scrap of paper says “Attention!” and “Thanks for Hospitality,” followed by “Was In A Rut.”

Per Sherwood, those words contain two secret messages, “CAN FBI CATCH ME” and “SWS.” He said SWS stands for the Special Warfare School, where Rackstraw would have learned the secret coding contained in the letters.

As a veteran of the Army Security Agency – a precursor to the National Security Agency that specialized in signals intelligence – Sherwood is familiar with the school because it’s where he learned the same coding.

During the Vietnam war, Sherwood served in the Army Security Agency’s signal-tracing chopper program called Project Left Bank. He said Rackstraw served briefly in his unit, but that he did not know Rackstraw personally.

The cold-case team found Rackstraw’s initials, RWR, and a reference to Rackstraw’s CIA ties in the coded message of the second D.B. Cooper missive. This note was sent in handwritten block letters on Nov. 30, 1971.

A representative for the CIA declined to comment on whether Rackstraw had ties to the agency.

Colbert’s team believes that D.B. Cooper sent the next letter on Dec. 1. 1971, to convey a message to his three accomplices.

Sherwood also said the initials for one of Rackstraw’s training units, the National Guard Jump School, is found upon decoding the fourth letter.

The FBI produced the above D.B. Cooper letter as part of a request under the Freedom of Information Act by investigator Thomas Colbert and his attorney, Mark Zaid.

The FBI kept a fifth letter about Cooper under wraps for decades before Colbert and his national-security attorney Mark Zaid unearthed it last year with a successful challenge under the Freedom of Information Act. Sherwood said a random string of numbers and letters at the bottom of the letter contained a reference to the Army Security Agency, his hill-top unit and Rackstraw’s first Vietnam unit.

Courthouse News went over Sherwood’s decoding methodology in a phone interview on the condition that it remain confidential since it will form a key part of the next D.B. Cooper documentary Colbert is producing.

Sherwood did note, however, that military codes are not made to be broken. In order to crack one, you need to know something about the individual who created it. Because of that, as he worked on deciphering any hidden messages in the letters, he had Rackstraw in mind.

He emphasized that the chances are slim that he just saw something he wanted to see that pointed to Rackstraw.

“If he in fact did not do it, then I wouldn’t have been able to match almost every word to his units,” Sherwood said. “It would have never added up. Because I knew every unit and I was in those units.”

(Courtesy of Thomas Colbert)

SKEPTICS & THE BUREAU

Promotional material by the History Channel in advance of a 2016 documentary on D.B. Cooper by Thomas Colbert.

Other Cooperites have proved almost as reluctant as the FBI meanwhile to get on board with Colbert’s team.

“I do not believe that any of the letters signed ‘DB Cooper’ are from the skyjacker, and Colbert does not offer substantial proof that any of them are,” said Bruce Smith, a former investigative reporter who self-published a book on D.B. Cooper in 2016.

Colbert has maintained, however, that the fifth D.B. Cooper letter contains information that only the hijacker and the FBI would know.

For example, it says that Cooper left no fingerprints behind, and that he wore a toupee and putty makeup during the hijacking.

Though Smith waved off Colbert’s findings as “quirky circumstantial evidence,” he said the material might inch Cooperites closer to the truth.

“To me, the evidence points to someone from Vietnam with covert commando training, with a high likelihood that he was a former smokejumper, too,” Smith said in an interview.

Colbert and his attorney Zaid also have a theory about why the FBI failed to act on more than 100 pieces of additional evidence they provided, including samples from a dig site where they believe they found pieces of Cooper’s parachute along with part of the ransom money.

One of several composite sketches of D.B. Cooper. (FBI)

“We do think now, having identified this individual, that the FBI is frankly embarrassed that they let him slip through their grasp back in the late ’70s,” attorney Zaid said during the Feb. 1 press conference.

The FBI put the D.B. Cooper investigation on the back burner in 2016, but public information officer Ayn Dietrich-Williams with the FBI’s Seattle Field Office said any physical items sent the bureau are reviewed and given an appropriate follow-up.

“The FBI continues to receive tips from members of the public, but none to date have resulted in a definitive identification of the hijacker,” Dietrich-Williams said in an email. “The tips have conveyed plausible theories, descriptive information about individuals potentially matching the hijacker, and anecdotes — to include accounts of sudden, unexplained wealth. In order to solve a case, the FBI must prove culpability beyond a reasonable doubt, and, unfortunately, none of the well-meaning tips or applications of new investigative technology have yielded the necessary proof.”

Dietrich-Williams noted in another email that the FBI does not necessarily provide updates to tipsters, who may be unaware of any actions the agency takes based on information provided.